In this article we will see how we can get data bounds of the line of line graph in the PyQtGraph module. PyQtGraph is a graphics and user interface library for Python that provides functionality commonly required in designing and science applications. Its primary goals are to provide fast, interactive graphics for displaying data (plots, video, etc.) A line chart or line plot or line graph or curve chart is a type of chart which displays information as a series of data points called ‘markers’ connected by straight line segments. It is a basic type of chart common in many fields. Line graph is created with the help of plot class in PyQtGraph. Data bounds is the range occupied by the line in x-axis or y-axis.
We can create a plot window and create lines on it with the help of commands given below
# creating a pyqtgraph plot window plt = pg.plot() # plotting line in green color # with dot symbol as x, not a mandatory field line = plt.plot(x, y, pen='g', symbol='x', symbolPen='g', symbolBrush=0.2, name='green')
In order to do this we use dataBounds method with the line object
Syntax : line.dataBounds(0)
Argument : It takes integer i.e 0 for x-axis and 1 for y-axis as argument
Return : It returns tuple
Below is the implementation
# importing Qt widgets from PyQt5.QtWidgets import * import sys
# importing pyqtgraph as pg import pyqtgraph as pg
from PyQt5.QtGui import *
# Bar Graph class class BarGraphItem(pg.BarGraphItem):
# constructor which inherit original
# BarGraphItem
def __init__( self , * args, * * kwargs):
pg.BarGraphItem.__init__( self , * args, * * kwargs)
# creating a mouse double click event
def mouseDoubleClickEvent( self , e):
# setting scale
self .setScale( 0.2 )
class Window(QMainWindow):
def __init__( self ):
super ().__init__()
# setting title
self .setWindowTitle( "PyQtGraph" )
# setting geometry
self .setGeometry( 100 , 100 , 600 , 500 )
# icon
icon = QIcon( "skin.png" )
# setting icon to the window
self .setWindowIcon(icon)
# calling method
self .UiComponents()
# showing all the widgets
self .show()
# method for components
def UiComponents( self ):
# creating a widget object
widget = QWidget()
# creating a new label
label = QLabel( "GeeksforGeeks Line Plot" )
# making it multiline
label.setWordWrap( True )
# y values to plot by line 1
y = [ 2 , 8 , 6 , 8 , 6 , 11 , 14 , 13 , 18 , 19 ]
# y values to plot by line 2
y2 = [ 3 , 1 , 5 , 8 , 9 , 11 , 16 , 17 , 14 , 16 ]
x = range ( 0 , 10 )
# create plot window object
plt = pg.plot()
# showing x and y grids
plt.showGrid(x = True , y = True )
# adding legend
plt.addLegend()
# set properties of the label for y axis
plt.setLabel( 'left' , 'Vertical Values' , units = 'y' )
# set properties of the label for x axis
plt.setLabel( 'bottom' , 'Horizontal Values' , units = 's' )
# setting horizontal range
plt.setXRange( 0 , 10 )
# setting vertical range
plt.setYRange( 0 , 20 )
# plotting line in green color
# with dot symbol as x, not a mandatory field
line1 = plt.plot(x, y, pen = 'g' , symbol = 'x' , symbolPen = 'g' , symbolBrush = 0.2 , name = 'green' )
# plotting line2 with blue color
# with dot symbol as o
line2 = plt.plot(x, y2, pen = 'b' , symbol = 'o' , symbolPen = 'b' , symbolBrush = 0.2 , name = 'blue' )
# getting data bounds of the line 1
value = line1.dataBounds( 0 )
# setting text to the label
label.setText( "Data_Bound : " + str (value))
# Creating a grid layout
layout = QGridLayout()
# setting this layout to the widget
widget.setLayout(layout)
# adding label to the layout
layout.addWidget(label, 1 , 0 )
# plot window goes on right side, spanning 3 rows
layout.addWidget(plt, 0 , 1 , 3 , 1 )
# setting this widget as central widget of the main window
self .setCentralWidget(widget)
# create pyqt5 app App = QApplication(sys.argv)
# create the instance of our Window window = Window()
# start the app sys.exit(App. exec ())
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Output :